[feature] Unused avatar and header cleanup (#574)

* rename + tidy up remote pruning

* fix media attachment account join
see https://bun.uptrace.dev/guide/golang-orm.html#table-relationships

* update logging to new function name

* add get avatars and headers to bun

* add pruneallmeta function

* don't set uncached since we're deleting anyway

* fix totalPruned being in wrong place

* test pruning meta

* go fmt ./...

* rename mediaprune

* add meta pruning to routine mediaprune

* tidy up cleanup job scheduling

* rename adminmediaremoteprune

* update mediacleanup to use renamed prune func

* update swagger docs a little bit

* reuse cancel + context

internal/media/prunemeta.go

@@ -0,0 +1,87 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package media
+
+import (
+	"context"
+
+	"codeberg.org/gruf/go-store/storage"
+	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+func (m *manager) PruneAllMeta(ctx context.Context) (int, error) {
+	var totalPruned int
+	var maxID string
+	var attachments []*gtsmodel.MediaAttachment
+	var err error
+
+	// select 20 attachments at a time and prune them
+	for attachments, err = m.db.GetAvatarsAndHeaders(ctx, maxID, selectPruneLimit); err == nil && len(attachments) != 0; attachments, err = m.db.GetAvatarsAndHeaders(ctx, maxID, selectPruneLimit) {
+		// use the id of the last attachment in the slice as the next 'maxID' value
+		l := len(attachments)
+		logrus.Tracef("PruneAllMeta: got %d attachments with maxID < %s", l, maxID)
+		maxID = attachments[l-1].ID
+
+		// prune each attachment that meets one of the following criteria:
+		// - has no owning account in the database
+		// - is a header but isn't the owning account's current header
+		// - is an avatar but isn't the owning account's current avatar
+		for _, attachment := range attachments {
+			if attachment.Account == nil ||
+				(attachment.Header && attachment.ID != attachment.Account.HeaderMediaAttachmentID) ||
+				(attachment.Avatar && attachment.ID != attachment.Account.AvatarMediaAttachmentID) {
+				if err := m.pruneOneAvatarOrHeader(ctx, attachment); err != nil {
+					return totalPruned, err
+				}
+				totalPruned++
+			}
+		}
+	}
+
+	// make sure we don't have a real error when we leave the loop
+	if err != nil && err != db.ErrNoEntries {
+		return totalPruned, err
+	}
+
+	logrus.Infof("PruneAllMeta: finished pruning avatars + headers: pruned %d entries", totalPruned)
+	return totalPruned, nil
+}
+
+func (m *manager) pruneOneAvatarOrHeader(ctx context.Context, attachment *gtsmodel.MediaAttachment) error {
+	if attachment.File.Path != "" {
+		// delete the full size attachment from storage
+		logrus.Tracef("pruneOneAvatarOrHeader: deleting %s", attachment.File.Path)
+		if err := m.storage.Delete(attachment.File.Path); err != nil && err != storage.ErrNotFound {
+			return err
+		}
+	}
+
+	if attachment.Thumbnail.Path != "" {
+		// delete the thumbnail from storage
+		logrus.Tracef("pruneOneAvatarOrHeader: deleting %s", attachment.Thumbnail.Path)
+		if err := m.storage.Delete(attachment.Thumbnail.Path); err != nil && err != storage.ErrNotFound {
+			return err
+		}
+	}
+
+	// delete the attachment entry completely
+	return m.db.DeleteByID(ctx, attachment.ID, &gtsmodel.MediaAttachment{})
+}